R package for circle packing. Algorithms to find arrangements of non-overlapping circles

This package provides functions to find non-overlapping arrangements of circles.

The function `circleRepelLayout`

attempts to arrange a set
of circles of specified radii within a rectangle such that there is
no-overlap between circles. The algorithm is adapted from an example
written in Processing by Sean McCullough (which no longer seems to be
available online). It involves iterative pair-repulsion, in which
overlapping circles move away from each other. The distance moved by
each circle is proportional to the radius of the other to approximate
inertia (very loosely), so that when a small circle is overlapped by a
large circle, the small circle moves furthest. This process is repeated
iteratively until no more movement takes place (acceptable layout) or a
maximum number of iterations is reached (layout failure). To avoid edge
effects, the bounding rectangle is treated as a toroid. Each circle’s
centre is constrained to lie within the rectangle but its edges are
allowed to extend outside.

The function `circleProgressiveLayout`

arranges a set of
circles, which are denoted by their sizes, by consecutively placing each
circle externally tangent to two previously placed circles while
avoiding overlaps. It was adapted from a version written in C
by Peter Menzel. The underlying algorithm is described in the paper:
*Visualization of large hierarchical data by circle packing* by
Weixin Wang et
al. (2006).

The function `circleRemoveOverlaps`

takes an initial set
of overlapping circles and attempts to find a non-overlapping subset or,
optionally, a subset with some specified degree of overlap. Circle
positions remain fixed. It provides several fast heuristic algorithms to
choose from, as well as two based on linear programming. For the latter,
package lpSolve must be installed.

The function `circleGraphLayout`

is an initial Rcpp port
of an algorithm described by Collins and
Stephenson (2003) to find an arrangement of circles which
corresponds to a graph of desired circle tangencies. The implementation
is based on a Python version by David Eppstein (see CirclePack.py in the
PADS library.

To install:

- the latest released version:
`install.packages("packcircles")`

- the latest development version:
`install_github("mbedward/packcircles")`

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